> Tor Egge <tegge@FreeBSD.org> writes:
> > Log:
> > Add SMP_TSC option, which can be used on SMP systems where the TSCs
> > are synchronized to reduce context switch cost.
>
> Out of curiosity, what kind of systems would that be?
Dell PowerEdge 2450, 2 x 733 MHz PIII CPUs, 1 GB memory.
Elapsed times of "dd if=/dev/da0s4g of=/dev/null bs=512 count=200000" test:
5.0-CURRENT 5.0-CURRENT 5.0-CURRENT 4.8-RELEASE 4.8-RELEASE
i8254 ACPI-safe TSC i8254 TSC
48.010578 35.460545 29.709355 13.326655 12.426712
48.041532 35.153883 29.797299 13.359450 12.411480
48.039143 35.113667 29.610601 13.349306 12.804534
47.630433 35.163372 30.036985 13.258281 12.473128
47.693183 35.240809 29.728361 13.332692 12.473128
Which gives average microseconds/read of
239 176 149 67 63
- Tor Egge